1. Field of the Invention
The present invention relates to a connecting arrangement for rotor blades of a turbomachine.
2. Brief Description of the Related Art
A rotor blade connecting arrangement of the type mentioned at the beginning is known from DE 35 17 283 C2. In this arrangement, projections are provided which extend in the circumferential direction, are rigidly connected in pairs to a rotor blade and are respectively supported by at least one pressure body on the projection which is adjacent in the circumferential direction. In this arrangement, each pressure body has a securing contour on a securing face which faces toward the associated projection, which securing contour protrudes into an acceptance feature configured on the associated projection and is supported, in the circumferential direction and transverse to it, in the acceptance feature. In addition, each pressure body has a plane support surface on a support face which faces toward the adjacent projection, which support surface has area support on a plane mating support surface associated with an adjacent projection. In the known rotor blade connecting arrangement, the securing contours of the pressure bodies are respectively configured as a cone. The associated acceptance features are likewise configured as a cone, the cone of the securing contour having, however, a conicity different from that of the cone of the acceptance feature. This achieves the effect that compensation can be provided for manufacturing tolerances of the seating surface and the pressure body due to slight plastic deformations at the outer edge of the cone acceptance feature and the cone securing contour. The mating support surface, on which the support surface of the pressure body is supported, can be formed, in a development of the known rotor blade connecting arrangement, by the support surface of a mating pressure body which has the same structure as the pressure body.
The known rotor blade connecting arrangement functions in an optimum manner if, during operation of the turbomachine, only relative motions extending parallel to the support surface occur. The support surface can then slide on the mating support surface. In practice, however, it is not only parallel-directed relative motions which occur between the mutually supporting or mutually connecting projections. Particularly when a turbine is being run up or run in certain low-load operating phases, for example during windage in the last turbine stage, twisting and torsion of the rotor blades, and therefore of the projections, can occur. This leads, in particular, to increased vibration loading on the blade connecting arrangement. Rotational motions between the projections, however, lead to a line or point loading of the respective pressure body acceptance feature, which can lead to a brittle fracture of the hard pressure body or to cracking of the pressure body seat.